While solid state light sources, e.g., light emitting diodes (LEDs) may generate less thermal energy compared to traditional bulbs (e.g., incandescent light bulbs), solid state light sources nevertheless generate thermal energy which should be managed in order to control the junction temperature. A higher junction temperature generally correlates to lower light output, lower luminaire efficiency, and/or reduced life expectancy. Solid-state illumination systems include heat sinks to dissipate thermal energy away from the solid state light source in order to manage the junction temperature.
It is known that solid-state light-emitting diodes (LEDs) are efficient and used in automotive low beam and high beam headlamps. Higher power LEDs are now used in such applications, such as those sold by OSRAM Opto Semiconductors under the trade designation Oslon, and can employ 8 chips to generate 1250 lumens. When using a passive heat sink, such LEDs need relatively large passive heat sinks, which may be heavy and present a lampset packaging concern. Even when using the higher power LEDs and passive heat sinks the radiated heat remains behind the headlamp housing's bezel which conceals the light source and the front lens cover stays relatively cool, too cool for the thermal power of these LEDs to melt ice or defog lenses, as was commonly done by the traditional but less efficient filament incandescent or halogen lamps, such as conventional H11 bulbs for a headlamp, which generated plentiful waste heat. Conventional solutions have involved hot air generating fans with complicated air ducts that required breaking holes into the bezel, undesirable from a standpoint of a vehicle manufacturer's styling goals.